1. Field of the Invention
The present invention relates to drying machines, and more particularly to a drying machine for drying articles such as clothes and semiconductor devices cleaned with an inflammable solvent used as a detergent without catching fire nor causing an explosion.
2. Description of the Prior Art
Drying of clothes cleaned (washed and rinsed) with an inflammable solvent involves a danger that the residual solvent in the clothes catches fire in the drying operation at a high temperature. Thus Japanese Unexamined Patent Publication No. SHO 60-2294/ 1985 proposes a clothes drying machine providing a gas sensor on the side of a gas evacuation channel at the outlet of a drying chamber. The gas sensor checks the clothes to be dried for the presence of a solvent gas to distinguish whether the clothes are cleaned with such solvent or with water. When the gas sensor detects the solvent gas, the drying machine dries clothes at a low temperature, thereby preventing clothes from catching fire and being involved in an explosion. Gas sensors for use in such clothes drying machines include a semiconductor type and a contact combustion type.
In addition, Japanese Patent Publication No. HEI 3-8797 proposes a clothes drying machine for drying clothes at a temperature lower than the ignition temperature of the inflammable solvent to inhibit a danger of catching fire and causing an explosion.
Any kind of gas sensor mounted in the former type of clothes drying machine is constituted so that it can detect the presence of gas by heating the detecting part of the gas sensor. Thus the detecting part of the gas sensor is very likely to catch fire. It means that a fire preventing means having an explosion resistant structure must be installed in the housing chamber of the gas sensor. Clothes drying machines are getting more and more complicated in structure and expensive in price. Furthermore, the gas sensor is exposed to the solvent gas for many hours. The gas sensor has a drawback of lacking in reliability since the solvent gas corrodes the gas sensor, which deteriorates the durability thereof and the precision in the detecting capabilities.
On the other hand, the latter type of clothes drying machine has a drawback that the drying operation is prolonged because clothes are dried at a low temperature even if such drying machine is safe and free from a danger of catching fire and causing an explosion.
Many such problems appear in the same manner when various kinds of semiconductor devices are cleaned with an inflammable solvent.